Britain's Land Rover BAR qualified for the America's Cup semi-finals on Thursday after winning a tactical duel with Groupama Team France, who had already been outclassed by SoftBank Team Japan as their hopes of reaching the semis faded.
Franck Cammas and his French team have only two points in the head-to-head contest, after losing six of their eight races.
The crew with fewest points after each has raced the other twice in the Louis Vuitton America's Cup Qualifiers will be eliminated, with the other challengers going into a semi-final.
Conditions on Bermuda's Great Sound tested the British and French crews more than the others, with Ben Ainslie's Land Rover BAR left standing in their race with Emirates Team New Zealand, who are themselves through to the semis on points.
Ainslie, who has had a difficult start to his America's Cup campaign, was left becalmed as the wind died away.
"Just to inform you we are retiring from the race," a visibly irritated Ainslie could be heard telling the umpire.
The loss left Land Rover BAR further behind Emirates Team New Zealand in the qualifying rankings and Ainslie's crew threw every trick possible into their next race against France to clinch victory, with the lead having swung back and forth.
SoftBank Team Japan had earlier shown their superior speed and foiling technique against Groupama Team France after their skipper Dean Barker got the better start and built on his lead.
Like the British, the French found themselves in the doldrums during the middle of the race, with Barker describing the light and flukey wind as the toughest he had faced so far.
"These conditions are probably the hardest we have for these boats," Barker said, adding that factors such as body movements on the finely-tuned 50-foot (15 metre) foiling catamarans were crucial when the wind was so light.
Groupama Team France, the pre-event underdogs, have struggled to get their 50-foot foiling catamaran to "fly" as well as the other five crews in the regatta, but in the light breeze Ainslie's crew fared no better.
"What happened?" Ainslie asked of his crew after a calamitous manoeuvre early in their race against New Zealand which left the most successful Olympic sailor ever rattled.
"They're killing us, just killing us," Ainslie added as New Zealand, helmed by another Olympian Peter Burling, sailed into the distance across the crystal clear Bermudan waters.
In the race between defender Oracle Team USA, skippered by Jimmy Spithill, and SoftBank Team Japan, the two catamarans were evenly matched for speed and time on their foils, but a good call by Oracle tactician Tom Slingsby allowed them to overhaul their opponents and keep them on top of the leaderboard.
Oracle Team USA as defender go straight through to the America's Cup Match but can gain a valuable bonus point if they manage to triumph over the other crews in the qualifying round.
(Reporting by Alexander Smith in London; Editing by Pritha Sarkar and Ken Ferris)